Survival of the fittest has been a law of nature since the beginning of life, but sometimes that struggle begins earlier than we might think. For baby sand tiger sharks, the fight literally begins even before they are born.

The female sand tiger has two wombs, but she does not have litters twice as large as other sharks. In fact, she only gives birth to two particularly strong, feisty pups. Newborn sand tiger sharks have keen eyesight and sharp teeth that have already tasted the blood of their siblings – or half siblings.

For almost any object in the sea, there’s a creature who will feed on it – even if it’s a whale skeleton or a shipwreck. Though not related to one another, boneworms and shipworms share the remarkable ability to locate their meals in the vast ocean. Boneworms consume the bones of mammals, fish, reptiles and other animals, while shipworms – actually a type of mollusk – use their tiny shells to burrow into the wood of wrecked ships, trees adrift, or other wooden structures in the sea. Despite having neither stomachs nor mouths, both boneworms and shipworms have symbiotic bacteria in their gut that release nutrients from the bones or wood which these “worms” absorb as food.

Perhaps you’ve heard of a full moon so bright you can read by its light. But what if you could also read by the light of ocean waves — at night, with no moonlight at all? If you’re in one of Puerto Rico’s famous “bioluminescent bays,” you might be able to. In these three bays, the water is full of tiny plankton called dinoflagellates which produce neon blue light called bioluminescence.

When we think of a pristine shoreline, we don’t usually picture man-made structures in the scene, but jetties and retaining walls are common sights along many waterways. Waves that continually crash against the shore release energy that can erode waterfront property. Bulkheads, retaining walls, and revetments are designed to protect shorelines by minimizing erosion. Over time, however, these structures may actually increase erosion by altering nature’s ability to replenish sensitive coastal areas.

Sometimes scientists searching for one thing stumble unexpectedly onto another. A few years ago, a research team did just that, they drilled into an Antarctic ice sheet and opened up a can of anemones — almost literally. When the Antarctic Geological Drilling (ANDRILL) Program lowered a 4.5- foot cylindrical robot through the ice off the coast of west Antarctica, they were hoping to use the robot’s two cameras to learn about ocean currents while gathering data for modeling the drill’s use. In the process, their cameras captured an icy garden of sea anemones that no one knew existed.

If Finding Nemo had been more scientifically accurate, it may have caught Disney fans off guard: Nemo’s dad, Marlin, would have become more than a single dad when Nemo’s mother died. Among clownfish, the most dominant male will actually transform into a female if the matriarch of the community dies. Clownfish generally spend their entire lives in one small area, making it difficult to find a new mate, especially one of the opposite sex.

Most people know that electricity and water don’t mix, but it’s not a problem for fish that produce their own electricity. The best-known electric fish is probably the electric eel, but it is far from the only “shocking” creature underwater. In fact, the electric eel, a single species that dwells only in the rivers of South America, is outnumbered by more than 60 species of electric rays that live in the oceans.

Seahorses and pipefish may be beautiful and graceful creatures, but they’re not the speediest of fish. In fact, they swim more slowly than most marine animals, yet they manage to catch some of the fastest prey in the sea nearly every time. Their secret weapon? Seahorses use their unusually shaped heads.

Getting a good whiff of your partner to decide if he’s the right man for you may sound familiar — a good cologne can certainly attract women as much as a nice perfume can pique a man’s interest. Similarly, female lobsters seek out their mates using males’ smell, but the details may not seem as familiar — or pleasant.

When most people think about math, they’re probably not thinking of marine creatures. Yet one of the most famous sequences of numbers in the world actually shows up throughout nature, including under the waves. Fibonacci numbers, named for the Italian mathematician who first identified them in the 1200s, show up in everything from starfish and sand dollars to dolphins and hurricanes.